Searching on Google reveals x2 code snippets. The first result is to this code recipe which has a lot of documentation and explanation, along with some useful discussion und
Current solution
A reference implementation of PEP 3143 (Standard daemon process library) is now available as python-daemon.
Historical answer
Sander Marechal's code sample is superior to the original, which was originally posted in 2004. I once contributed a daemonizer for Pyro, but would probably use Sander's code if I had to do it over.